Friction damper

ABSTRACT

To provide a friction damper with simple construction having characteristics that there is little difference in resistance forces between at initial shock and after slide, and it is difficult to deform slide member under large fastening force, and large frictional force can stably be generated. The friction damper  1  comprising: a cylinder box  2 ; a cylinder member  6  axially fixed in the cylinder box; a slide bearing  7  press-fitted into an inner peripheral surface of the cylinder member; and a shaft  3  made of metal, the shaft being axially slidably press-fitted into an inner peripheral surface of the slide bearing; wherein when the cylinder box and the shaft move axially in relation to each other, an outer peripheral surface of the shaft and the inner peripheral surface of the slide bearing frictionally slide in relation to each other to absorb vibration energy. When the friction damper of the present invention is mounted to an intermediate portion or an end portion of a structural member of a building structure such that the cylinder box and the shaft relatively axially movable with each other, and repeated tensile and compressive forces are added to the structural member of the building structure due to earthquake or the like, the inner peripheral surface of the slide bearing press-fitted into the cylinder member and the outer peripheral surface of the shaft frictionally slide with each other to absorb vibration energy.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to International Application No.PCT/JP2007/062882 which was filed on Jun. 27, 2007 and claims priorityto Japanese Patent Application No. 2006-180992 filed on Jun. 30, 2006.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

The present invention relates to a friction damper, and moreparticularly to a friction damper mounted between a pair of structuralmembers of a building structure that relatively displaces with eachother when repeated tensile and compressive forces are added thereto dueto earthquake or the like and absorbing the energy.

2. Description of the Related Art

As dampers for rapidly attenuating vibration of structures generated byearthquake or the like are there one utilizing plastic deformation ofsteel bars and lead, one utilizing viscous shear of viscous material,one utilizing friction and so on.

In the dampers utilizing steel bars, when the steel bars greatly deformto cause plastic deformations due to earthquake or the like, it isnecessary to consider replacement of the steel bars each time, and whenreplacing them, it is required to pay attention to a method of releasingresidual stress acting on the steel bars.

On the other hand, as for the dampers utilizing lead, there is a threaton environmental pollution, and when utilizing viscous material isutilized, not only long period of time is required for filling work ofthe viscous material, but also it is necessary to mount seal meanscapable of securely preventing leakage.

Further, the dampers utilizing frictional force are advantageous insimple construction and easy handling compared with the above-mentioneddampers, and the following ones are known.

For example, a vibration suppression damper described in the patentdocument 1 comprises: a cylinder body having a connection part connectedto a member of a building; a rod with a connection part connected to theother member of the building; a holding cylinder mounted to the rodthrough a viscoelastic member; a slide member mounted through an elasticrepellent member that applies a uniform urging force to an outerperiphery of the holding cylinder and urged by the elastic-repellentmember in a direction of outer periphery, and on the outer periphery ofthe slide member is provided a friction member slidingly contact with aninner periphery of the cylinder body.

Moreover, in the patent document 2, an energy absorbing device for astructural member is proposed. The energy absorbing device comprises: acontainer box formed of an outer frame and an inner frame that areaxially slidable with each other; a dice fixed to an inside of eitherone of the inner frame or the outer frame; a fitting-in rod fixed to theother frame and extending through a hole of the dice in an axialdirection of the container box, in which the hole diameter of the diceis set smaller than the outer diameter of the fitting-in rod and thefitting-in rod is a steel rod that is made to pass through the dice andhardened in advance, when a cyclic load of overtension andovercompression more or equal to a prescribed strength acts to astructural member, the energy absorbing device for the structural memberabsorbs energy while a part of the fitting-in rod passing through thedice deforming.

Further, in the patent document 3, a friction damper is disclosed. Thefriction damper comprises: a base body; a support member adhered to along member of the base body and having a throughhole; a rod extendingthrough the throughhole of the support member and relatively movable tothe support member in an axial direction of the rod; a friction memberhaving a cylindrical part interposed between the support member and amain body portion of the rod in the throughhole of the support memberand fixed to be immobile in relation to an axial movement of the rodrelative to the base body; a fastening means provided to the supportmember to fasten the cylindrical part of the friction member to the mainbody portion of the rod.

Further, in the patent document 4 is described a slide friction damper.The slide friction damper comprises: an inner cylinder part to which arubber elasticity part consisting of self-lubricity rubber is adheredand fixed through vulcanization fabrication; an arm part attached to theboth ends of the inner cylinder part; an inner cylinder fitting withrubber elasticity body bonded thereto, the rubber elasticity body beingpress-fitted into an outer cylinder part; the outer cylinder part madeof stainless steel as a low friction material; an outer cylinder fittingwith a support bar fixed on its outer peripheral surface and protrudingin a radial direction thereof; and a cylindrical rubber elastic bodypart elastically connecting the inner and outer cylinder fittings.

Patent document 1: Japanese Utility Model Publication Showa 63-115642gazette

Patent document 2: Japan Patent 3290912 gazette

Patent document 3: Japan Patent Publication 2003-278828 gazette

Patent document 4: Japanese Patent Publication 2004-3563 gazette

BRIEF SUMMARY OF THE INVENTION

As described above, dampers utilizing various frictional forces exist,although the vibration suppression damper described in the patentdocument 1 attenuates vibration energy by frictional resistancegenerated between the inner peripheral surface of the cylinder body andthe outer peripheral surface of the friction member urged by the spring,the urging mechanism itself is complicated, in addition to that, a largeurging force is required to obtain large frictional resistance force,which causes a problem that the spring becomes too large.

Moreover, the energy absorbing device for structural member described inthe patent document 2 absorbs energy by deformation of a portion of thefitting-in rod passing through the dice when the fitting-in rod, whichis hardened in advance, passes the hole of the dice smaller thandiameter thereof, but special processing was required for the fitting-inrod itself, further when using it, since it was necessary to payattention to that a difference in resistance force between at initialshock and after slide becomes large, grease, lubrication oil, or thesolid lubricant is needed to be applied in advance to an innerperipheral surface of the dice or/and an outer peripheral surface of thefitting-in rod as occasion demands.

On the other hand, the friction damper described in the patent document3 is invented by the present applicant, and energy is absorbed by thefriction between the slide layer made of synthetic resin, which isformed on a face of the base material with net body and is also filledin meshes of the net body, and the rod, and optimal frictionalresistance can be obtained by the fastening means, further it is afriction damper with high stability with little difference in resistanceforce between at initial shock and after slide.

However, in order to obtain larger resistance force, when largerpressure is applied by the fastening means to the slide memberconsisting of the slide layer made of synthetic resin, which is formedon a face of the base material with net body and is also filled inmeshes of the net body, the slide member deforms since the memberconsists of base material with net body, which causes a problem that adesired pressure cannot be added.

Moreover, although the slide friction damper described in the patentdocument 4 attenuates vibration by causing the self-lubricating rubberto contact the metal fittings with the rubber being compressed andthrough friction generated between the self-lubricating rubber and themetal fitting, since the self-lubricating rubber is used, the frictionalforce acquired is set small, so that the damper is unsuitable for commonstructures.

The present invention has been made in consideration of the problems inthe above conventional techniques, and the object thereof is to providea friction damper with simple construction having characteristics thatthere is little difference in resistance forces between at initial shockand after slide, and it is difficult to deform slide member under largefastening force, as a result, large frictional force can stably begenerated.

Further, it is another object of the present invention to provide adamper, even plurality of friction members are connected andincorporated therein, having characteristics that difference in degreeof friction among plurality of friction members is considerably little,so that there is no partial abutment and others.

To achieve the above object, the present invention relates to a frictiondamper, and this damper is characterized by comprising: a cylinder box;a plurality of cylinder members axially fixed in the cylinder box; aclearance formed between an outer peripheral surface of each cylindermember and an inner peripheral surface of the cylinder box; a slidebearing press-fitted into an inner peripheral surface of the cylindermember; and a shaft made of metal, the shaft being axially slidablypress-fitted into an inner peripheral surface of the slide bearing;wherein when the cylinder box and the shaft move axially in relation toeach other, an outer peripheral surface of the shaft and the innerperipheral surface of the slide bearing frictionally slide in relationto each other to absorb vibration energy.

When the friction damper of the present invention is mounted to anintermediate portion or an end portion of a structural member of abuilding structure such that the cylinder box and the shaft relativelyaxially movable with each other, and repeated tensile and compressiveforces are added to the structural member of the building structure dueto earthquake or the like, the inner peripheral surface of the slidebearing press-fitted into the cylinder member and the outer peripheralsurface of the shaft frictionally slide with each other to absorbvibration energy, which provides a friction damper with simpleconstruction and excellent reliability and safety. In addition, whenlarge frictional force is required, there is a clearance between theouter peripheral surface of each cylinder member and the innerperipheral surface of the cylinder box, so that it becomes possible tocoincide the center of each bearing and that of one press-fitted shaftwith each other, which provides a friction damper causing neitherpartial abutments in frictional slide surface nor trouble at thepress-fitting work.

In the friction damper of the present invention, the slide bearingincludes a multi-layered member in which a metal layer on an outerperipheral surface side, a coat layer on an inner peripheral surfaceside made of synthetic resin compound for coating the metal layer and ajunction layer for joining the metal layer and the coat layer areintegrally formed with each other. Since the slide surface against theouter peripheral surface of the shaft made of metal is formed to besynthetic resin compound, adhesion phenomenon between the members aredifficult to occur, which makes difference in resistance forces betweenat initial shock and after slide little. In addition, large fasteningforce, which is generated when the metal shaft is press-fitted into theinner peripheral surface of the slide bearing, is added to the coatlayer of synthetic resin compound as a slide surface, the syntheticresin compound is supported by the junction layer, and further it isdifficult to generate deformation in the overall slide bearing due tostiffness of the metal layer, so that stable frictional slides and adesired large frictional force can simultaneously be acquired.

Especially, in case that a damper is used for antiseismic reinforcementconstruction, sometimes, it may not be clearly grasped the strength offixed part of an existing structure to which the damper is mounted, sothat it is necessary to eliminate unstable factors on the performance ofthe damper as much as possible so as not to generate an unexpectedsituation like damage of the fixed part to which the damper is mounted.In this respect, in the friction damper of the present invention, asdescribed above, there is no threat of increase in frictional resistanceforce due to adhesion on frictional surface, and difference infrictional performance between at initial shock and after slide islittle, resulting in excellent reliability and safety.

Further, in the friction damper, the junction layer may be a porousbronze sintered layer. With this, synthetic resin compound as the coatlayer can securely be held.

In the friction damper, the synthetic resin compound may bepolytetrafluoroethylene resin containing a filler, and as the filler,one or at least two selected from a group consisting of heat-resistantresin, reinforcing fiber, orthophosphate and solid lubricant can beused.

In the friction damper, the slide bearing may be formed by rolling the fwith the coat layer being inside.

Further, in the friction damper, the slide bearing may have a flangeportion at an end portion of a cylindrical bearing portion. Insertingthe flange portion between opposing sides of adjacent cylinder membersprevents axial movement of the slide bearing when axial vibration isadded. In addition, the slide bearing can be extracted out of thecylinder member as occasion demands, so that consumable parts can easilybe replaced and it is preferable in maintenance side of the frictiondamper.

In the friction damper, plurality of the cylinder members can axially befixed in the cylinder box, and a clearance may be formed between anouter peripheral surface of each cylinder member and an inner peripheralsurface of the cylinder box. With this, especially when large frictionalforce is added like the present invention, there is a clearance betweenthe outer peripheral surface of the cylinder member and the innerperipheral surface of the cylinder box, so that it becomes possible tocoincide each center of each of the slide bearings and the center of onepress-fitted shaft, which causes neither partial abutments in frictionalslide surface nor trouble at the press-fitting work.

As described above, with the present invention, it becomes possible toprovide a friction damper with simple construction capable of stablygenerating large frictional force, and so on, since there is littledifference in resistance forces between at initial shock and afterslide, and it is difficult to deform slide member under large fasteningforce.

In addition to the above effect, with this invention, in a damper, inwhich even plurality of friction members are connected and incorporatedtherein also, it is possible to make difference in degree of frictionamong plurality of friction members considerably little, which preventsgeneration of partial abutments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1( a) is a front view of a friction damper according to anembodiment of the present invention;

FIG. 1( b) is a cross-sectional view taken along the line A-A of FIG. 1(a);

FIG. 1( c) is an enlarged view of the encircled region B of FIG. 1( b);

FIG. 2( a) is a front view of a housing of the friction damper shown inFIG. 1( a);

FIG. 2( b) is a cross-sectional view taken along the line C-C of FIG. 2(a);

FIG. 3( a) is a front view of a bearing of the friction damper shown inFIG. 1( a);

FIG. 3( b) is a side view of the bearing shown in FIG. 3( a);

FIG. 4 is a detailed partial cross-sectional view of the bearing of thefriction damper shown in FIG. 3;

FIG. 5 is a schematic view showing an example of use of the frictiondamper shown in FIG. 1( a);

FIG. 6 is a hysteresis curve of a friction damper according to thepresent invention; and

FIG. 7 is a graph showing resistance force and an applied vibrationcycle of a friction damper according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Next, embodiments of the present invention will be explained in detailwith reference to the figures.

FIG. 1( a) shows a friction damper according to an embodiment of thepresent invention, and the friction damper 1 comprises: a cylinder(cylinder box) 2 and a rod (shaft) 3 relatively movable with each otherin an axial direction X and; three housings (cylinder members) 6 axiallyfixed in the cylinder 2 by a pressure support pipe 4 and a fasteningpipe 5; three slide bearings (hereinafter referred to as “bearings”) 7,each of them press-fitted into each inner peripheral surface of thehousing 6; and mounting parts 8, 9 mounting the friction damper 1 toconstruction members or the like of a building structure.

The cylinder 2 is, as shown in FIG. 1( b), integrally formed with a leftend portion of the mounting part 9 at a right end portion thereofthrough screw fastening, and a joint of the two parts is filled withcalking agent to improve weatherability. To the mounting part 9 arescrewed bolts 10 to mount the part 9 to a building structure.

In the cylinder 2 is disposed the cylindrical pressure support pipe 4 soas to abut a left side face of the mounting part 9. Between thispressure support pipe 4 and the fastening pipe 5 connected through screwto a left end portion of the cylinder 2 are mounted three sets ofhousings 6 and bearings 7.

The housing 6 is, as shown in FIGS. 2( a) and 2(b), formed to becylindrical, and the inner diameter of the bearing 7 press-fitted intothe housing 6 is slightly smaller than the outer diameter of the rod 3,which allows the rod 3 to always be tightened.

The bearing 7 is, as shown in FIGS. 3( a) and 3(b), in addition to acylindrical bearing portion 7 a, provided with a flange portion 7 bintegrally formed with the cylindrical bearing portion 7 a, and thecylindrical bearing portion 7 a has a slit 7 f that is generated whenmanufacturing the bearing 7 through rolling. This flange portion 7 b is,as shown in FIG. 1( c), inserted between opposing sides of adjacenthousings 6, and the overall bearing 7 is fixed to be immobile inrelation to a movement of the rod 3 relative to the cylinder 2 in theaxial direction X.

Further, the bearing 7 comprises, as shown in FIG. 4, metal layer(back-metal layer) 7 c coated with copper; porous bronze sintered layer(junction layer) 7 d with pores that is formed by scattering andspreading bronze powder to one surface of the metal layer 7 c andsintering the powder; and a coat layer 7 e that is formed by filling thepores in the porous bronze sintered layer 7 d and coating the surface ofthe porous bronze sintered layer 7 d with polytetrafluoroethylene resincontaining a filler, and the bearing 7 is manufactured by whollysintering these materials and rolling them by a roll to a prescribedthickness to manufacture a multi-layered member, and further rolling themulti-layered member such that a face on the coat layer 7 e side of themulti-layered member is placed on the inner diameter side and anotherface on the metal layer 7 c side is placed on the outer diameter side,further attaching the flange portion 7 b to prevent slip-off.

Meanwhile, a synthetic resin compound used for the coat layer of thebearing 7 may be, besides polytetrafluoroethylene resin containing afiller, synthetic resin compound based on polyamide-imide resin.

Further, the filler used for the coat layer of the bearing 7 is madefrom one or at least two selected from a group consisting ofheat-resistant resin, reinforcing fiber, phosphate and solid lubricant,for instance, the heat-resistant resin may be polyimide resin, thereinforcing fiber may be carbon fiber, the phosphate can be calciumphosphate and the solid lubricant may be graphite.

As shown in FIG. 1( b), the rod 3 is provided with a male screw portion3 b at a left end portion of a cylindrical main body 3 a, and the malescrew portion 3 b is screwed with a female screw portion 8 a of themounting part 8 as well as a nut 11 for preventing slip-off. Outside ofthe rod 3 adjacent to the nut 11 is mounted a cover 12, and a right endportion of the cover 12 is fixed to the fastening pipe 5 through thebolt 13, and a left end portion of the cover 12 is caused to slidablycontact the sealing material 14. In addition, into the hole portion 8 bof the mounting part 8 is inserted a pin 15 for mounting the frictiondamper 1 to a building structure.

Next, a method of assembling the friction damper 1 with theabove-mentioned construction will be explained with reference to FIGS.1( a), 1(b) and 1(c).

At first, as illustrated in FIG. 1( b), to a right end portion of thecylinder 2 is mounted the mounting part 9 through screw fastening, andbetween the cylinder 2 and the mounting part 9 is filled calking agent.Then, from a left opening of the cylinder 2 is inserted the pressuresupport pipe 4 into the cylinder 2, and a right end portion of thepressure support pipe 4 is caused to abut a left end portion of themounting part 9.

Three housings 6 with inner peripheral surfaces into which the bearings7 are press-fitted are inserted into the cylinder 2 from the leftopening of the cylinder 2, and a rightmost end portion of the rightmosthousing 6 is caused to abut the left end portion of the pressure supportpipe 4. Under this condition, as shown in FIG. 1( c), there areclearances S between the outer peripheral surfaces 6 a of the housings 6and the inner peripheral surface 2 a of the cylinder 2. In addition, theclearances S are different in dimension among the housings 6, forinstance, due to processing precisions of the outer peripheral surfaces6 a of the housings 6 and the inner peripheral surface of the cylinder2. Next, to a left end portion of the cylinder 2 is mounted thefastening pipe 5 through screw fastening.

Meanwhile, after the nut 11 is screwed to the male screw portion 3 b ofthe rod 3, the female screw portion 8 a of the mounting part 8 is causedto be screwed to the male screw portion 3 b, and the nut 11 is fasteneduntil an left end portion thereof abuts a right end portion of themounting part 8 to unify the rod 3 and the mounting part 8.

A right end portion of the rod 3 is inserted into the cylinder 2 fromthe left opening of the cylinder 2, and the rod 3 is moved right whilethe outer peripheral surface of the rod 3 sliding the inner peripheralsurface of the bearing 7 to obtain the condition shown in FIG. 1( b). Inthis case, even though the bearings 7 and the housings 6 are machined soas to have the same dimensions with each other and press-fittings areperformed in the same condition, there is a threat that centralpositions of the plurality of bearings 7 differ, so that when the rod 3is press-fitted into the plurality of bearings 7 under the conditionthat the outer peripheral surfaces of the housings 6 are flush with eachother, differences may be generated among the central position of therod 3 and the central positions of the bearings 7, which may causepartial abutments between the rod 3 and each bearing 7, resulting in athreat of difficulty in press-fitting work of the rod 3 itself.

Therefore, in this invention, as shown in FIG. 1( c), the housings 6 areaxially fixed in the cylinder 2 with clearances S between the outerperipheral surfaces of the housings 6 and the inner peripheral surfaceof the cylinder 2, so that, in the press-fitting work of the rod 3, therod 3 can be press-fitted under the condition that each of the housings6 into which the bearings 7 are press-fitted is movable in an directionvertical to the axial direction such that the center of the rod 3 andthe centers of the bearing 7 coincide with each other, which allowsdifferences may not be produced among conditions of frictional surfacesbetween each of the bearing 7 and the rod 3.

Next, to the outside of the rod 3 is mounted a cover 12; the right endportion of the cover 12 is fixed to the fastening pipe 5 through thebolt 13; and the left end portion of the cover 12 is caused to slidablycontact the sealing material 14. Finally, the bolts 10 are screwed tothe mounting part 9, and the pin 15 is inserted into the hole portion 8b of the mounting part 8 to complete assembling of the friction damper1.

In this connection, to assemble the friction damper 1, besides the abovemethod, the following method may be used.

In FIG. 1( b), to the right end portion of the cylinder 2 is mounted themounting part 9 through screw fastening, and between the cylinder 2 andthe mounting part 9 is filled the caulking agent. Then, from the leftopening of the cylinder 2 is inserted the pressure support pipe 4 intothe cylinder 2, and the right end portion of the pressure support pipe 4is caused to abut the left end portion of the mounting part 9.

Next, after the nut 11 is screwed to the male screw portion 3 b of therod 3, the female screw portion 8 a of the mounting part 8 is screwed tothe male screw portion 3 b, and the nut 11 is fastened until the leftend portion of the nut 11 abuts the right end portion of the mountingpart 8 to unify the rod 3 and the mounting part 8.

Then, under the condition that the fastening pipe 5 passes from a rightend of the rod 3, from the right end of the rod 3, the rod 3 is insertedwhile the outer peripheral surface thereof sliding the inner peripheralsurface of each of the bearings 7 of three housings 6 with innerperipheral surfaces into which the bearing 7 are press-fitted to disposethe three housings 6 to predetermined positions on the rod 3.

After that, under the condition that the fastening pipe 5 passes throughthe rod 3 that is integral with the mounting part 8, the rod 3, to whicheach of the housings 6 into which the bearings 7 are press-fitted arearranged at predetermined positions thereon, is inserted from the leftopening of the cylinder 2 until the left end of the pressure supportpipe 4 arranged in the cylinder 2 abuts the right end of the housing 6,and the fastening pipe 5 is caused to screw to a screw portion on a leftend inner diameter side of the cylinder 2 to fix the three housings 6 soas not to move in an axial direction.

Next, on the outside of the rod 3 is mounted the cover 12, and the rightend portion of the cover 12 is fixed to the fastening pipe 5 through thebolt 13, and the left end portion of the cover 12 is caused to slidablycontact the sealing material 14. Finally, to the mounting part 9 arescrewed the bolts 10, and into the hole portion 8 b of the mounting part8 is inserted the pin 15 to complete assembling of the friction damper1.

With the above assembling method, it becomes possible to eliminatepartial abutments between the rod 3 and each of the bearings 7, that is,it becomes possible not to generate differences in conditions offrictional surfaces between each of the bearings 7 and the press-fittedrod 3.

Next, example of use and motion of the friction damper 1 with theabove-mentioned construction will be explained with reference todrawings.

FIG. 5 shows a case that the friction damper 1 is used for a buildingstructure, and between a lower beam 21A and an upper beam 21B, thefriction dampers 1 (1A to 1D) are mounted between obliquely arrangedsteel pipe braces 22 (22A, 22B) and brackets 24 and the like. Forexample, the friction damper 1 (1A) is connected to the bracket 24 bythe pin 15 shown in FIG. 1, and is connected to the oblique steel pipebrace 22A by the bolts 10. Meanwhile, for instance, constructing themounting part 8 rotatable to the rod 3 allows the friction damper 1 tobe mounted to the bracket 24 with ease.

Under the condition shown in the figure, due to earthquake or the like,relative displacement is generated between the lower beam 21A and theupper beam 21B, the cylinder 2 of the friction damper 1 (1A) and the rod3 (refer to FIG. 1( b)) relatively move with each other in a directionindicated by the arrow D to absorb vibration energy. That is, in FIG. 1(b), the cylinder 2 and the rod 3 relatively move with each other in thedirection indicated by the arrow X.

During the movement of the rod 3 in relation to the cylinder 2 in thedirection indicated by the arrow X, friction between the innerperipheral surfaces of the bearings 7 and the outer peripheral surfaceof the rod 3 absorbs vibration energy generated in the structure, andvibration of the structure is settled in an early stage.

With this friction damper 1, at the relative movement between the rod 3and the cylinder 2, as shown in FIG. 1( c), each of the flange portions7 b of the bearings 7 is held by opposing sides of adjacent housings 6,and each of the flange portions 7 b is fixed to be immobile in relationto the movement of the rod 3 relative to the cylinder 2 in the directionindicated by the arrow X, which allows each of the bearings 7 tosecurely be fixed to prevent shift of each bearing 7 in position to eachhousing 6.

Further, as shown in FIG. 4, the coat layer 7 e of the bearing 7 as aslide surface is a layer of polytetrafluoroethylene resin containing afiller, so that the friction damper 1 can be used without lubricant, andis excellent in dimension stability, mechanical strength and heatconductivity, and the coat layer 7 e is thin, resulting in lighter andsmall sized friction damper 1.

Meanwhile, in the above embodiment is used the bearing 7 withmulti-layered member comprising: the metal layer 7 c of the bearing 7;the porous bronze sintered layer 7 d as a junction layer integrallyformed on a surface of the 7 c; and the coat layer 7 e of syntheticresin compound filled in pores of the porous bronze sintered layer 7 dand coating the surface of the porous bronze sintered layer 7 d, inplace of the porous bronze sintered layer 7 d as a junction layer forjointing the metal layer 7 c and the coat layer 7 e, the metal layer andthe synthetic resin compound may be jointed by bonding agent when it isstrong such that they can be jointed steadily under large fasteningforce, further they can be jointed directly.

In addition, in the above embodiment, the housing 6 and the bearing 7are arranged three by three, that is, three sets of the housings 6 andthe bearings 7 are disposed, the both may be arranged one by one, andtwo or four sets or more may be disposed.

Next, example of test on the friction damper 1 will be explained withreference to FIGS. 6 and 7.

Displacement and resistance force of the rod 3 were measured when thecylinder 2 of the friction damper 1 with the construction shown in FIG.1 was fixed and the rod 3 was caused to axially move in relation to thecylinder 2. Here, as the bearing 7 was used a polytetrafluoroethyleneresin multi-layered member bearing with back metal comprising a metallayer, porous bronze sintered layer as a junction layer and apolytetrafluoroethylene resin as a coat layer, in which the rod 3 of190.7 mm in outer diameter and 1350 mm in length was used and a highspeed testing machine capable of applying up to 3000 kN was used. Theresult is shown in FIG. 6.

In the figure, the axis of abscissas shows axial slide displacement (mm)of the rod 3, and the axis of ordinates shows resistance force (kN)required to slide the rod 3, and the graph is a hysteresis when theslides of the rod 3 are repeated eleven times. With the graph, it isunderstood that there is little difference between resistance forces atinitial shock and that after slide, and almost the same resistance forceis added each time even the slides are repeated.

FIG. 7 shows the change in resistance force in each cycle at the abovetest. With the graph, it is understood that the resistance force in eachcycle is almost the same regardless of the number of times that theslides are repeated.

EXPLANATION OF REFERENCE NUMBERS

-   1 friction damper-   2 cylinder-   2 a inner peripheral surface-   3 rod-   3 a main body portion-   3 b male screw portion-   4 pressure support pipe-   5 fastening pipe-   6 housing-   6 a outer peripheral surface-   7 bearing-   7 a bearing portion-   7 b flange portion-   7 c metal layer-   7 d porous bronze sintered layer-   7 e coat layer-   7 f slit-   8 mounting part-   8 a female screw portion-   8 b hole portion-   9 mounting part-   10 bolt-   11 nut-   12 cover-   13 bolt-   14 sealing material-   15 pin-   21A lower beam-   21B upper beam-   22(22A, 22B) steel pipe brace-   24 bracket-   S clearance

1. A friction damper comprising: a cylinder box; a plurality of cylindermembers axially fixed in said cylinder box, a clearance being formedbetween an outer peripheral surface of each of the cylinder members andan inner peripheral surface of the cylinder box; a slide bearingpress-fitted into an inner peripheral surface of said cylinder member;and a shaft made of metal, said shaft being axially slidablypress-fitted into an inner peripheral surface of said slide bearing;wherein when the cylinder box and the shaft move axially in relation toeach other, an outer peripheral surface of said shaft and the innerperipheral surface of said slide bearing frictionally slide in relationto each other to absorb vibration energy.
 2. The friction damper asclaimed in claim 1, wherein said slide bearing includes a multi-layeredmember in which a metal layer on an outer peripheral surface side, acoat layer on an inner peripheral surface side made of synthetic resincompound for coating said metal layer and a junction layer for joiningthe metal layer and the coat layer are integrally formed with eachother.
 3. The friction damper as claimed in claim 2, wherein saidjunction layer is a porous bronze sintered layer.
 4. The friction damperas claimed in claim 2, wherein said synthetic resin compound ispolytetrafluoroethylene resin containing a filler.
 5. The frictiondamper as claimed in claim 4, wherein said filler is one or at least twoselected from a group consisting of heat-resistant resin, reinforcingfiber, phosphate and solid lubricant.
 6. The friction damper as claimedin claim 2, wherein said slide bearing is formed by rolling themulti-layered member with the coat layer being inside.
 7. The frictiondamper as claimed in claim 1, wherein said slide bearing has a flangeportion at an end portion of a cylindrical bearing portion. 8.(canceled)
 9. The friction damper as claimed in claim 3, wherein saidsynthetic resin compound is polytetrafluoroethylene resin containing afiller.
 10. The friction damper as claimed in claim 3, wherein saidslide bearing is formed by rolling the multi-layered member with thecoat layer being inside.
 11. The friction damper as claimed in claim 4,wherein said slide bearing is formed by rolling the multi-layered memberwith the coat layer being inside.
 12. The friction damper as claimed inclaim 5, wherein said slide bearing is formed by rolling themulti-layered member with the coat layer being inside.
 13. The frictiondamper as claimed in claim 2, wherein said slide bearing has a flangeportion at an end portion of a cylindrical bearing portion.
 14. Thefriction damper as claimed in claim 3, wherein said slide bearing has aflange portion at an end portion of a cylindrical bearing portion. 15.The friction damper as claimed in claim 4, wherein said slide bearinghas a flange portion at an end portion of a cylindrical bearing portion.16. The friction damper as claimed in claim 5, wherein said slidebearing has a flange portion at an end portion of a cylindrical bearingportion.
 17. The friction damper as claimed in claim 6, wherein saidslide bearing has a flange portion at an end portion of a cylindricalbearing portion.